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你好,
我是一个经验丰富的PSoC应用程序设计员。我使用PSoC 5LP。我有一个应用程序,使用opAMP V1.90。 大多数时候,我需要用模式= OpAMP配置OpAmp。“-”输入被路由到电流检测电阻器的外部引脚。然而,由于1MEG欧姆输入阻抗(观察到但在数据表中没有指定),由于额外的绘制和合成噪声,我不能解决电流的30UA。 如果我“硬”配置模式=跟随器,我可以解决非常低的电流到1uA,噪音低得多。 我想在optAMP中配置opAMP到模式=opAMP,当需要解析1UA时,在运行时的代码中切换到模式=跟随器。如果需要的话,我可以在寄存器级操作,但是如果有一些API调用来提供这一点,那就太好了。 注:我尝试使用模拟多路复用器外部的运算放大器来执行这个期望的功能。我注意到许多成功的问题,不得不放弃尝试。 谢谢你的帮助。 伦恩 以上来自于百度翻译 以下为原文 Hi, I'm a seasoned PSoC application designer. I'm using a PSoC 5LP. I have an application that uses the OpAmp v1.90. Most of the time I need to configure the OpAmp with a mode = OpAmp. The '-' input is routed to an external pin of a current sense resistor. However due to the < 1Meg ohm input impedance (observed but not specified in the datasheet), I cannot resolve to < 30uA of current due to the extra draw and resultant noise. If I "hard" configure the mode = Follower, I can resolve very low currents to ~ 1uA with much lower noise. I want to configure the OpAmp to mode = OpAmp in the TopDesign and switch to mode=Follower in the code at run0time when needing to resolve to 1uA. I can operate at the register level if needed but it would be nice if there were some API calls to provide this. Note: I tried using a analog mux external to the OpAmp to perform this desired function. I noticed many problems doing this successfully and had to abandon the attempt. Thanks for the help in advance. Len |
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8个回答
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伦恩,
你能解释你如何衡量在从动模式1ua电流? ODISSEY1 以上来自于百度翻译 以下为原文 Len, can you explain how you measure 1uA current in Follower mode? /odissey1 |
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ODISSEY1
Opamp被用作当前感测电路的功率刺激。当刺激在一个模式中使用(满量程范围0至20mA)时,我需要+/-100uA精度(模式:OpAmp与外部引脚连接到'-'输入)。在另一种模式(模式:跟随者没有外部引脚连接到' - '输入),我需要+/-1uA精度(满量程范围0至1.4Ma)。我可以得到这个1UA精度,如果我强迫这个模式为模式:跟随者。我正在寻找一种在运行时切换OPAMP模式设置的方法,以提高所需模式下的性能。 伦恩 以上来自于百度翻译 以下为原文 odissey1, The Opamp is being used as the power stimulus for the current sense circuit. When the stimulus is used in one mode (full scale range 0 to 20mA), I need +/- 100uA accuracy (Mode:OpAmp with an external pin connected to the '-' input). In another mode (Mode: Follower with NO external pin connection to '-' input), I need +/-1uA accuracy (full scale range 0 to 1.4mA). I can get this 1uA accuracy if I force this mode to Mode: Follower. I'm looking for a means to switch this Opamp mode setting on-the-fly at run-time to improve performance in the needed mode. Len |
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xyz628 发表于 2018-10-1 06:55 Len,我希望有一个简图,我只能猜测安排。你能在运放的“-”输入前面加一个跟随器作为高阻抗输入缓冲器吗? 关于寄存器访问。我会向塞浦路斯的支持者提起诉讼。但我对他们的回答并不乐观。 ODISSEY1 以上来自于百度翻译 以下为原文 Len, I was hoping for a schematic, I can only guess about arrangement. Can you add a follower in front of "-" input of the opamp to serve as high-impedance input buffer? Regarding the register access. I would file a case with Cypress support. But i wouldn't be much optimistic about their answer. /odissey1 |
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nvwuwy 发表于 2018-10-1 07:10 下面是我写的两个配置。每一个作品的精度,我需要的,如果我'硬'编译示意图。 伦恩 以上来自于百度翻译 以下为原文 Here's two configurations I'm writing about. Each works to the accuracy I need if I 'hard' compile the schematic. Len |
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伦恩, 我会尝试添加在反馈路径的缓冲器,它可以消除的opamp_1低输入阻抗的影响。 以上来自于百度翻译 以下为原文 Len, I would try to add a buffer in the feedback path, which should eliminate effect of low input impedance of the Opamp_1. |
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用户手册 如果我使用缓冲器(OpPAMS2)的建议,我会遇到同样的问题,因为OpPAMS1’’端子的输入阻抗与OpAMPU2’+’端子的阻抗相同(注意:这些端子的输入阻抗不是由塞浦路斯指定)。它们的规格线存在,但没有表示值。此外,如果在端口PII之间使用另一个缓冲器,则由于增益和输入偏移误差容易出现潜在的错误。因此,OpPAMS2的输出将不太准确。 当我想测量1UA分辨率时,需要在模式中至少需要4MEG输入阻抗。移除PY2的内部连接并配置OpAMPHI1到MODE =跟随器工作,因为PY2在这个配置中与OpAMPU1的'-'终端具有4Meg以上的隔离。 伦恩 以上来自于百度翻译 以下为原文 user_342122993, If I use the buffer (OpAmp_2) suggestion I run into the same issue since the input impedance of Opamp_1 '-' terminal is the same as the impedance of Opamp_2 '+' terminal (Note: The input impedance of these terminals are not specified by Cypress. They spec line exists but no value is stated). Additionally if I use another buffer between port P_2, it is prone to potential error due to gain and input offset errors. Therefore the output of Opamp_2 would be less accurate. It comes to the idea that need a minimum of 4Meg input impedance in the mode when I want to measure 1uA resolution. Removing the internal connection to P_2 and configuring Opamp_1 to mode=Follower works because the P_2 has more than 4Meg isolation to the '-' terminal of Opamp_1 in this configuration. Len |
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xyz628 发表于 2018-10-1 07:49 你好, 在CYWDR,您可以看到切换地址,如果您在交换机上徘徊,则启用跟随模式。尝试编写此寄存器运行时间。 以上来自于百度翻译 以下为原文 Hi, In CYWDR you can see the switch address which enables the follower mode if you hover over the switch. Try writing this register run time. |
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USERY41084676, 谢谢您。我已经按照你的建议去做了。此外,我需要断开先前连接到“--”终端的开关,否则终端连接到两个模拟源。 伦恩 以上来自于百度翻译 以下为原文 user_411084576, Thank you. I've done what you suggested. In addition, I needed to disconnect a switch previously connected to the '-' terminal as well otherwise the terminal is connected to two analog sources. Len |
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